play the natural minor scale, we notice that there is a full tone or full step between the 7th and 1st note which would be a minor 7th. The reason for this is something like a cadence. In this case it's a vii-I cadence. A MAJOR cadence was MUCH more useful to classical composers due to how well the Major 7th resolved back to the 1. The minor 7th is ok and works well, but they thought it'd be a good idea to use a Major 7th in a natural minor scale. Thus, the harmonic minor scale was born. As ...